去除航空影像上的像點高差和像片傾斜移位的真正射影像，可提供正確的幾何和輻射資訊作為新拍影像的控制之用。然而去除像點高差移位時，通常必須費時費力地獲取地形地物的精確高程。因此本文提出在未知精確高程資訊下由兩張以上已知方位的航空影像產生真正射影像區塊的方法，試驗中採用"浮測面"的概念產生某一高程範圍內對應某一平面地形的數組候選正射影像區塊。每一組候選正射影像區塊對應一特定高程，接著發展演算法決定一組最佳正射影像區塊，最後將這組正射影像區塊融合成一真正射影像區塊。由初步試驗成果證實所提方法的可行性。 Orthoimages can be used as control information to determine the exterior orientation of new aerial images. For that purpose, the image displacements on aerial images due to photographic tilt and topographic relief (including the height of topographic objects) should be exactly removed to generate "true" orthoimages. Thus the correct geometrical and radiometric information can be provided from them for control information. However it is always time-consuming and labour-intensive to capture the accurate heights of terrain area for removing the image displacements from topographic relief. Therefore, this paper will propose a methodology to generate the orthoimage patches from multiple aerial images without capturing accurate terrain heights. In the proposed method, a concept of floating plane, similar to the concept of floating mark, will be presented to produce several orthoimage candidate sets for a terrain area at some height range from multiple aerial images. Each orthoimage candidate set consists of several related orthoimage patches for a terrain area at some specific height. Subsequently, a procedure will be developed to decide an optimal orthoimage set for this terrain area among those orthoimage candidate sets. While the optimal orthoimage set is decided, the height information is also determined. After that, a unique orthoimage patch for this terrain area will be fused from this optimal ortlloimage set. The relevant assessment of accuracy is also discussed and conducted in this paper. The preliminary experiments prove the feasibility of the proposed method.